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' I TED STATES PATENT QFFICE.

BENJAMIN CZTILGHMAN 'A'Nn moi-[Ann A. TILGIIMAN, or lI-IlLADELPl-IIA,

PENNSYLVANIA.

:"G HlL L ED-illwN c -oeuuz.

SPECIFICATION. forming part of Letters Patent No. 446,988, 24,1891.

' Application filed Iarqh 17, 1890. 9am No. 344.234. (Bpeoi|nene.)

, To all whom it may concern;

Be it'known that we, BENJAMIN C. TILGH- -'MAN and RICHARD'A. TIL HMAN,both of the city and county. of Philadelphia, State of Pennsylvania,have invented a certain new and usefiul Improvement in Chilled-IronGlob- -ules,of which the following is a true and exact description,reference being bad to the accompanying drawings, which form a part ofthis specification. J Our-invention relates to the manufacture ofchilled-iron globules such as are used in the process of abrasiondescribed in 13.0. Tilghmans patent, Reissue No, 7,499, dated February6, 1877, and also to some extentin the sand-blast process. vTheseglobules are manufacturedbyatolnizingastreamof melted iron by means of a5 ct of high-pressure steam assume a 'sphericalform and chill on thesurface, so as to take a permanent set or form. The still intensely-hotglobules are then permitted to fall into a tank of water, where 2 5 theyare chilled to an intense hardness. They arethen removed \irom /thewater and dried preparatory to packing them forshipment. At two stagesof this method ofjmanufactu're the globules arefexposed to a rapidoxida- 0 tion-namely,when the melted iron is sprayed v in the air-,-when a burning aetiongtakes place on-thc surface of the globules; withformer tion of a crust or scales of oxide, and during the process ofdrying, when a dark-red fria- 3'5 ble coat of rust formsupon them. 5

In thetreatment t some delicate stones trouble has been met with fromthe rust-coat? ingot the globules staining the surface, and

where the globules are used for frosting metal r 0 the rust is driveninto the metal under treatment, discoloring and injuring the surface,The coating is also unsightly, and, owing to its friable nature, itsoils anything it comes in contact with.

5 The object of our invention is furnish the globuleswith a bright cleanmetallic surinsuch awaytlnatthey-will-nemainin :0 the air for a timelong enough for them to face, while retaining the desirable physical'qualities they have heretofore had; Of sev- ,eral methods for obtainingthe globulesof this kind with which wehave experimented the followingis,.we believe, the best: We spray the melted metal in a non-oxidizingatmosphere, one, for instance, from which the 'oxygen has beeneliminated, as by passing air through adeep bed of ignited fuel.- Thisprevents the direct oxidation of the globules of melted-metal and theyfall'iuto the watertank with" bright surfaces. The globules, whilecovered by waten'are not subjectto any-noticeable oxidation; butpreferably we dissolve a little lime or other alkali in said water. Wethen remove the globules from t the tank and pourover them a solution oflime in-waten/which should preferably con- -tainasinall proportion offincly-divided hy drate of, limein suspension. J This lime-water ordilute whitewash displaces the plain water, and the globules may afterthis treatment be safely handled and dried without danger of ,rustin'g.The reason for this is because the oxygen of the air is unable to rustan iron surface even in presenceof water without the presence of treecarbonic acid in solution, and free carbonic acid is of course impossi-jble in a solution containing lime orrother al- 7 s kali in excess, tor,the carbonic acid combines with the alkali, forming, for instance, carbonate of lime, and the free lime in suspension then dissolves,maintaining the saturation or I the solution, this chemical action goingon until the glohulesfare entirely dryand free from any considerabledanger of rusting, even it their protecting :shield of alkali wasabsent, whichit is notes of course a film of lime is depisited overthem. Of course the chilling-tank may be filled with the dilutewhitewash and the globules dried immediately on removal; but the use ofthe lime-water or whitewash, as described, is more economical, and forother reasons We go believe preferable,

" Instead of using the lime-water to prevent rusting, the globules maybe dried in unenchilled and hardened bright unoxidized meoxidizingatmosphere with the same results, tallic surface with a protecting film01f lime except asto the forma'tionpf the lime-film. deposited upon it.

.Havizig now described our-inventiemwhat 1 B. C. TILGHMAN. 5 we claim asnew, and desire tosecnre byLgtters Patent, is- Witnesses' as to 15.10.Tilghme-m' 1'. As a, newirarticle' of manufaeture, a ARTHUR'C. HALL, Achilled-iron glebulehaving anunpolished but; "IIENRYv BLAIR, j- I 1chilled and hardened bright unoxidized me- QMmmt 86., Manchestev 1otallie surface. I Witnesses as to R. A. Tilghman'r As a new article ofmanufacture, a LEWIS R. DICK,

chilled-iron globule having an un polished but JOSHUA MATLAOK, J r.

R. A. TILGHMQN,

